linux-kernel - Re: [PATCH v3] block: add check that partition length needs to be aligned with block size

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Message-ID: <93db2fcb-7afa-776e-01a1-de928b93e799@nvidia.com>
Date:   Thu, 29 Jun 2023 01:04:18 +0000
From:   Chaitanya Kulkarni <chaitanyak@...dia.com>
To:     Min Li <min15.li@...sung.com>
CC:     "axboe@...nel.dk" <axboe@...nel.dk>,
        "dlemoal@...nel.org" <dlemoal@...nel.org>,
        "hch@....de" <hch@....de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...nel.org" <stable@...nel.org>,
        "willy@...radead.org" <willy@...radead.org>
Subject: Re: [PATCH v3] block: add check that partition length needs to be
 aligned with block size

On 6/28/23 10:07, Min Li wrote:
> On Mon, Jun 28, 2023 at 04:48:36PM +0000, Christoph Hellwig  wrote:
>> They are long long in the UAPI, which is weird but has been that way
>> for a long time.  So I think we need checks for negative values
>> before they are shifted and converted to a sector_t.
> Do you mean that we need to check if p.start and p.length are negative?
>
> Thanks for your reply
>
> Min li

I think so, from include/uapi/linux/blkpg.h:-

/* The data structure for ADD_PARTITION and DEL_PARTITION */
struct blkpg_partition {
         long long start;                /* starting offset in bytes */
         long long length;               /* length in bytes */
         int pno;                        /* partition number */
         char devname[BLKPG_DEVNAMELTH]; /* unused / ignored */
         char volname[BLKPG_VOLNAMELTH]; /* unused / ignore */
};

so start and length can take -ve, hence in your patch we need to error
out instead inviting overflow bugs right after or before IS_ALIGNED
check.

-ck